Obama’s top counterterrorism adviisor John Brennan visited Israel Wednesday, after traveling to Bulgaria earlier this week to confer on the investigation into the July 18 Burgas bus bombing.

Brennan visited Israel July 25 “to consult with senior Israeli officials about a range of shared security concerns, including the recent wave of terrorist plots against Israeli and other interests,” NSC spokesman Tommy Vietor said in a statement Wednesday. Brennan also met with Palestinian Prime Minister Salam Fayyad.

Bulgarian Prime Minister Boyko Borisov said Tuesday after meeting with Brennan that Bulgarian authorities now believe the suspected suicide bomber in the Burgas bus bombing had been in the country for about a month, and had worked as part of a group with a high degree of discipline.

“These are extremely experienced people who observed absolute secrecy,” Borisov said at a press conference with Brennan July 24th, Agence France Press reported.

The July 18th attack, which targeted a bus of Israeli tourists who had arrived in the Black Sea resort town on a charter flight, killed seven people, including five Israeli tourists, their Bulgarian bus driver, and the suspected bomber.

Israeli Prime Minister Benjamin Netanyahu said Sunday that Israel has rock-solid evidence the attack was perpetrated by Hezbollah.